Heraclitus

Heraclitus (535 BC-475 BC) was a Presocratic Greek philosopher who was famous for his insistence on ever-present change, as well as for noting the difference between a "becoming" and "being".

Biography
Heraclitus was born in Ephesus, Ionia, Persian Empire in 535 BC, and he was of distinguished parentage. He led a lonely life, and he was nicknamed "the Obscure" and "the Weeping Philosopher" for his eternal sadness. Heraclitus insisted on ever-present change as being the fundamental essence of the universe, saying that "No man ever steps in the same river twice" (once a person stepped in a river, it was no longer the same river as it was before the person stepped in it). Heraclitus believed that the very nature of living was change, all things were in flux, that nobody could trust in stability, and that nothing had a permanent identity. Heraclitus died in 475 BC.